Exchange bias through a Cu interlayer in an Ir Mn ∕ Co system

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Efforts have been recently made to use remanence plots in exchange-bias studies. However, since the two remnant magnetizations of a biased loop may differ, this technique cannot be applied in its classical form. This work extends it to systems with shifted loops and shows that the number of distinct plots is significantly increased. The approach was probed on Co/IrMn exchange bias films. Possible discrepancies between experiment and theory are pointed out and discussed. The adaptation of the model presented here enables it to become one of the few accessible techniques for rapid and accurate evaluation of magnetic interactions in biased systems. V C 2013 AIP Publishing LLC.

Section: Resultsmentioning

confidence: 84%

Remanence plots technique extended to exchange bias systems

Harres

Cichelero

Pereira

et al. 2013

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“…18,31,34,43 Our samples, however, show H Regardless of the type, parallel or antiparallel, of the M/m rot coupling and its strength (J 0 ), H C of an FM/AF bilayer should be enhanced if compared to that of the respective control FM film due to the additional energy necessary to reverse an anisotropic UCS. The same holds for the RA, always positive for J 0 > 0.…”

Section: Resultsmentioning

confidence: 99%

“…(1); more details can be found elsewhere. 18,30,31 Differently from the previously employed domain-wall formation model, 32 we use uniaxial UCSs as FM's pinning sites instead of interfacial AF domain wall. Note that m set kŝ for very high k set and the model is reduced 33 to the rigid AF moment (RAF) model.…”

Section: Resultsmentioning

confidence: 99%

Antiparallel interface coupling evidenced by negative rotatable anisotropy in IrMn/NiFe bilayers

Schafer

Grande

Pereira

et al. 2015

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Negative rotatable anisotropy is estimated via ferromagnetic resonance measurements in as-made, annealed, and ion-irradiated IrMn 3 /Ni 81 Fe 19 bilayers. Opposite to previous observations, inverse correlation between rotatable anisotropy and coercivity is observed. The exchange-bias field, determined from hysteresis loop measurements, is higher than that obtained from ferromagnetic resonance for all samples. The results are discussed in terms of majority antiparallel coupling and magnetic-field-induced transitions from antiparallel to parallel states of uncompensated spins at ferromagnet/antiferromagnet interface. We affirm that an observation of negative rotatable anisotropy evidences antiparallel coupling even in systems presenting conventional exchange bias. V C 2015 AIP Publishing LLC. [http://dx

“…This difference could be attributed to the interplay between two opposing effects: ͑i͒ the role of the Cu spacer for the increase in K eff by reorienting the Co moment toward the perpendicular to the film's plane direction; ͑ii͒ the exponential decrease in J E ͑and, consequently, of H EB ͒ with the thickness of the nonmagnetic ͑NM͒ interlayer in FM/NM/AF films ͑see, e.g., Ref. 23 and references therein͒.…”

Section: Resultsmentioning

confidence: 99%

Cone magnetization state and exchange bias in IrMn∕Cu∕[Co∕Pt]3 multilayers

Castro

Geshev

Schmidt

et al. 2009

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The effects of a Cu interlayer on the perpendicular exchange bias in IrMn/ Cu/ ͓Co/ Pt͔ 3 multilayers were investigated by focusing on the correlation between the exchange bias and the magnetic anisotropy. The in-plane magnetization hysteresis loops were interpreted in the framework of a phenomenological model based on the coherent magnetization rotation, indicating that the easy magnetization axis makes an angle of approximately 15°with the normal of the IrMn/ ͓Co/ Pt͔ 3 film. This angle decreases with the introduction of the Cu spacer thickness in the IrMn/ Cu/ ͓Co/ Pt͔ 3 system, indicating that the Cu interlayer leads to a predominant perpendicular anisotropy. Although a maximum of the out-of-plane anisotropy is found for Cu layer thickness between 4 and 5 Å, the maximum of the perpendicular exchange bias was found at 3 Å of Cu, which could be attributed to the interplay between two effects, mainly the increase in the effective perpendicular anisotropy with the Cu spacer thickness due to the reorientation of the Co moment toward the normal to the film's plane direction, and the exponential decrease in the ferromagnet/antiferromagnet exchange coupling ͑and, consequently, of the exchange bias shift field͒ with the Cu interlayer thickness.